Seen a few posts in here indicating there is a constant need to calibrate your PH sensor if you are using it for an automatic feed system so it is reading correctly. I personally have the same problem with our PH sensors we use at work for treating chemicals so they are at appropriate levels before going to the city waste system
I am a controls person so i'm automating my own chlorine dispense system I have it mostly complete but haven't integrated the feedback system. I will need an ORP sensor and a controller that allows me to have 2 setpoints (low and very low sanitizer). I found some reasonable ORP sensors and controllers I could use from the fish tank industry that has contacts I can do my controls from but was curious if they or all ORP sensors exhibit the same need to constantly calibrate as PH sensors do.
If I have to go and constantly tweak my sensor it may not be worth the cost/trouble. I will just fine-tune the daily dispense amounts on my own(flow control). Anyone have any experience with ORP sensors and caibration reliability? Anyone know of any specific low-end brands sensor/controller that are resonable????